From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752294Ab3HOWtN (ORCPT ); Thu, 15 Aug 2013 18:49:13 -0400 Received: from mail-lb0-f170.google.com ([209.85.217.170]:33929 "EHLO mail-lb0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751481Ab3HOWtM (ORCPT ); Thu, 15 Aug 2013 18:49:12 -0400 MIME-Version: 1.0 In-Reply-To: <20130815223917.27890.28003.stgit@bling.home> References: <20130815223917.27890.28003.stgit@bling.home> Date: Fri, 16 Aug 2013 08:49:10 +1000 Message-ID: Subject: Re: [PATCH] i915: Update VGA arbiter support for newer devices From: Dave Airlie To: Alex Williamson Cc: "intel-gfx@lists.freedesktop.org" , Dave Airlie , LKML , =?ISO-8859-1?Q?Ville_Syrj=E4l=E4?= Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 16, 2013 at 8:43 AM, Alex Williamson wrote: > This is intended to add VGA arbiter support for Intel HD graphics on > Core processors. The old GMCH registers no longer exist, so even > though it appears that i915 participates in VGA arbitration, it doesn't > work. On Intel HD graphics we already attempt to disable VGA regions > of the device. This makes registering as a VGA client unnecessary since > we don't intend to operate differently depending on how many VGA devices > are present. We can disable VGA memory regions by clearing a memory > enable bit in the VGA MSR. That only leaves VGA IO, which we update > the VGA arbiter to know that we don't participate in VGA memory > arbitration. We also add a hook on unload to re-enable memory and > reinstate VGA memory arbitration. I would think there is still a VGA disable bit on the Intel device somewhere, we'd just need Intel to look in the docs and find it. A bit that can nuke both i/o and cmd regs. Dave.